What is the best way to prevent tropical hardwood deck lumber like ironwood from developing a gray patina in sunlight?

From
john schultz of o-gee paint co on
November 17, 2014:The surface of wood breaks down from sunlight and biological attack, leaving a gray deadwood patina that comes off relatively easily with a gentle pressure washing or abrading. Unfortunately, these hardwoods are very unforgiving and do not readily accept film-forming preservatives. Regular maintenance with cleaning and application of non-film forming oils will keep it looking rich. But these oils leach out and break down, too, and must be replaced about yearly to maintain appearances. A bit of trans-oxide pigment in the oil slows the decay and helps make the surface look more uniform, not a very long term solution, though. Decks are relatively easy to maintain as opposed to furniture with its myriad of visible, but difficult-to-reach areas.